Plasmon gate

ABSTRACT

A variety of structures, methods, systems, and configurations can support plasmons for logic.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to and claims the benefit of theearliest available effective filing date(s) from the following listedapplication(s) (the “Related Applications”) (e.g., claims earliestavailable priority dates for other than provisional patent applicationsor claims benefits under 35 USC § 119(e) for provisional patentapplications, for any and all parent, grandparent, great-grandparent,etc. applications of the Related Application(s)).

RELATED APPLICATIONS

-   -   For purposes of the USPTO extra-statutory requirements, the        present application constitutes a continuation-in-part of U.S.        patent application Ser. No. 11/471,288, entitled Plasmon Switch,        naming Roderick A. Hyde, Edward K. Y. Jung; Nathan P. Myhrvold,        John Brian Pendry, Clarence T. Tegreene, and Lowell L. Wood, Jr.        as inventors, filed 19 Jun. 2006, which is currently co-pending,        or is an application of which a currently co-pending application        is entitled to the benefit of the filing date.

The United States Patent Office (USPTO) has published a notice to theeffect that the USPTO's computer programs require that patent applicantsreference both a serial number and indicate whether an application is acontinuation or continuation-in-part. Stephen G. Kunin, Benefit ofPrior-Filed Application, USPTO Official Gazette Mar. 18, 2003, availableat http://www.uspto.gov/web/offices/com/sol/og/2003/week11/patbene.htm.The present Applicant Entity (hereinafter “Applicant”) has providedabove a specific reference to the application(s) from which priority isbeing claimed as recited by statute. Applicant understands that thestatute is unambiguous in its specific reference language and does notrequire either a serial number or any characterization, such as“continuation” or “continuation-in-part,” for claiming priority to U.S.patent applications. Notwithstanding the foregoing, Applicantunderstands that the USPTO's computer programs have certain data entryrequirements, and hence Applicant is designating the present applicationas a continuation-in-part of its parent applications as set forth above,but expressly points out that such designations are not to be construedin any way as any type of commentary and/or admission as to whether ornot the present application contains any new matter in addition to thematter of its parent application(s).

All subject matter of the Related Applications and of any and allparent, grandparent, great-grandparent, etc. applications of the RelatedApplications is incorporated herein by reference to the extent suchsubject matter is not inconsistent herewith.

SUMMARY

In one embodiment, a method of controlling energy propagation comprisesguiding energy at a first plasmon frequency along a first path, blockingthe guided energy at the first plasmon frequency from propagating alongthe first path responsive to a first signal at a first time, blockingthe guided energy at the first plasmon frequency from propagating alongthe first path responsive to a second signal, different from the firstsignal, at a second time, and receiving an output that is a function ofthe first signal and the second signal.

In another embodiment, a plasmon gate comprises a first plasmon guideextending from an input location to an output location, a first plasmonswitch interposed at a first central location intermediate the inputlocation and output location and responsive to a first signal, and asecond plasmon switch interposed at a second central locationintermediate the input location and output location and responsive to asecond signal, wherein the first switch and the second switch arearranged to control plasmon propagation to the output location.

In another embodiment, a method comprises inputting a plasmon signal,selectively controlling the plasmon signal with a plurality of controlsignals, and outputting a plasmon signal having a distribution that is afunction of the plurality of control signals.

In another embodiment, an apparatus comprises a plasmon input receptiveto a first plasmon signal, a first control input receptive to a firstcontrol signal, a second control input receptive to a second controlsignal, and a plasmon output configured to output a second plasmonsignal as a function of the first plasmon signal, the first controlsignal and the second control signal.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic of a plasmon at a boundary.

FIG. 2 is a schematic of an array of particles.

FIG. 3 is a schematic of a first path intersecting a second path.

FIG. 4 is a schematic of a first path intersecting a second path.

FIG. 5 is a schematic of a top cross-sectional view of a plasmon logicelement.

FIG. 6 is a schematic of a top cross-sectional view of a plasmon logicelement including an array of particles.

FIG. 7 is a schematic of a system including a plasmon logic element.

FIG. 8 is a schematic of a top cross-sectional view of a plasmon logicelement.

FIG. 9 is a schematic of a top cross-sectional view of a plasmon logicelement.

FIG. 10 is a schematic of a plasmon logic element configured on a fiber.

FIG. 11 is a schematic of a first embodiment of a plasmon gate.

FIG. 12 is a table corresponding to FIG. 11.

FIG. 13 is a schematic of a second embodiment of a plasmon gate.

FIG. 14 is a table corresponding to FIG. 13.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here.

Surface plasmons may exist on a boundary between two materials when thereal parts of their dielectric constants ∈ and ∈′ have different signs,for example between a metal and a dielectric. FIG. 1 shows a plasmon 102at a boundary 104 of a material 106 having a negative real dielectricconstant, such as a metal. The material or structure 108 forming theboundary 104 with the material 106 may be: air, vacuum, or itsequivalent; a substantially homogeneous dielectric material; or adifferent material or structure. The boundary 104, although shown asbeing substantially continuous and planar, may have a different shape.The plasmon 102, although shown as including substantially exponentialfunctions with a field maximum at the boundary 104, may include onlyapproximately exponential functions, may be described by a differentfunction, and/or may have a field maximum someplace other than theboundary. Further, although the plasmon 102 is shown at a certainlocation on the boundary 104 for illustrative purposes, the spatialdistribution of the plasmon 102 may be anything. Plasmons are describedin C. Kittel, “INTRODUCTION TO SOLID STATE PHYSICS”, Wiley, 2004, whichis incorporated herein by reference.

In some embodiments the material thickness 110 may be smaller than theplasmon wavelength, as described in Alexandra Boltasseva, ThomasNikolajsen, Krisjan Leosson, Kasper Kjaer, Morten S. Larsen, andSergey 1. Bozhevolnyi, “INTEGRATED OPTICAL COMPONENTS UTILIZINGLONG-RANGE SURFACE PLASMON POLARITONS”, Journal of Lightwave Technology,January, 2005, Volume 23, Number 1, which is incorporated herein byreference. Further, Boltasseva describes how a metal may be embedded ina dielectric to allow propagation of long-range surface plasmonpolaritons, where the parameters of the metal [including thickness 110and width (not shown)] may control the propagation of the plasmon.

Particles 202 may be configured to support and guide surface plasmons,where the particles 202 shown in FIG. 2 are silver spheres. Particlessupporting plasmons are described in M. Salerno, J. R. Krenn, B.Lamprecht, G. Schider, H. Ditlbacher, N. Felidj, A. Leitner, and F. R.Aussenegg, “PLASMON POLARITONS IN METAL NANOSTRUCTURES: THEOPTOELECTRONIC ROUTE TO NANOTECHNOLOGY”, Opto-Electronics Review, 2002,Volume 10, Number 3, pages 217-222, which is incorporated herein byreference. Creation of plasmons on a particle in an electromagneticfield is described in P. G. Kik, A. L. Martin, S. A. Maier, and H. A.Atwater, “METAL NANOPARTICLE ARRAYS FOR NEAR FIELD OPTICAL LITHOGRAPHY”,Proceedings of SPIE, 4810, 2002 which is incorporated herein byreference. FIG. 2 shows electromagnetic energy 206 incident on a chainof particles 202, where the particles 202 are coated with a nonlinearmaterial 204, and the electromagnetic energy 206 couples to plasmons 102on the particles 202. The plasmons 102 are shown having a finite extentin FIG. 2 for clarity and one skilled in the art will recognize that thespatial distribution of the plasmons 102 may fall off according to apower law away from the particles 202 and/or may have a differentdistribution than that shown in FIG. 2. Particles 202 may be configuredon a substrate (not shown), as described in Stefan A. Maier, Paul E.Barclay, Thomas J. Johnson, Michelle D. Friedman, and Oskar Painter,“LOW-LOSS FIBER ACCESSIBLE PLASMON WAVEGUIDE FOR PLANAR ENERGY GUIDINGAND SENSING”, Applied Physics Letters, May 17, 2004, Volume 84, Number20, Pages 3990-3992, which is incorporated herein by reference.

Particles 202 may be coated with nonlinear material 204, as described inN.-C. Panoiu and R. M. Osgood, Jr., “SUBWAVELENGTH NONLINEAR PLASMONICNANOWIRE”, Nano Letters, Nov. 10, 2004, Volume 4, Number 12, Pages2427-2430, which is incorporated herein by reference. In FIG. 2 all ofthe particles 202 are coated with a nonlinear material 204, however, insome embodiments only one particle may be coated with nonlinear material204, or a different number of particles 202 may be coated with nonlinearmaterial 204. Further, although FIG. 2 shows the particles 202completely coated with nonlinear material 204, one or more particles 202may only be partially coated with nonlinear material 204.

Although the particles 202 in FIG. 2 are shown as being substantiallyspherical, the particles may have a different shape that is configuredto support plasmons. Further, although the particles 202 are shown asbeing substantially the same size, the particles 202 may vary in size,by design or by a randomized process of manufacturing the particles 202.Moreover, the particles need not be homogenous or even solid. Also,although the particles 202 are described as silver particles, particles202 that support plasmons may comprise a different metal or a differentmaterial. Although the particles 202 are illustrated as having a spacingbetween particles 208 that is substantially constant, the spacing mayvary and may be different from that shown in FIG. 2, and in someembodiments, the particles 202 may be touching or very nearly so.

FIG. 3 shows a top cross-sectional view of a first embodiment includinga first path 302 for guiding energy at a first plasmon frequency, asecond path 304 for guiding energy at a second plasmon frequency, wherethe first path 302 and the second path 304 form an intersection region306 including a nonlinear material or other material configured tosaturate in response to a plasmon that forms a first portion of thefirst path 302. The paths 302, 304 are boundaries 104 as described withrespect to FIG. 1. An input coupling structure 310 is configured toconvert incoming electromagnetic energy 312 into a plasmon 102 (shown inFIG. 1) that propagates along the first path 302, and an output couplingstructure 314 is configured to convert a plasmon 102 propagating alongthe first path 302 into outgoing electromagnetic energy 316. Similarly,a second input coupling structure 318 is configured to convert incomingelectromagnetic energy 320 into a plasmon 102 (shown in FIG. 1) thatpropagates along the second path 304, and a second output couplingstructure 322 is configured to convert a plasmon 102 propagating alongthe second path 304 into outgoing electromagnetic energy 324.Electromagnetic energy 320 converted into a plasmon 102 propagatingalong the second path 304 can saturate the intersection region 306 andthus inhibit the propagation of a plasmon 102 through the intersectionregion 306 along the first path 302.

Although the embodiment in FIG. 3 is described such that theintersection region 306, when saturated, inhibits propagation of aplasmon 102 through the intersection region 306, in another embodimentthe intersection region 306 may be configured to allow propagation of aplasmon 102 when it is saturated and inhibit or restrict propagation ofa plasmon 102 when it is not saturated.

Some methods for coupling electromagnetic energy to a plasmon (and viceversa) that may be incorporated in an input and/or output couplingstructure 310 and/or 314 are described in W. L. Barnes, A. Dereux, andT. W. Ebbesen, “SURFACE PLASMON SUBWAVELENGTH OPTICS”, Nature, Volume424, Aug. 14, 2003, 824-830, which is incorporated herein by reference.These methods include and are not limited to prism coupling, scatteringfrom a topological defect on the surface on which the plasmon is to begenerated, and periodic corrugation in the surface on which the plasmonis to be generated.

In some approaches the input and output coupling structures 310, 314,318, 322 may be integral to the first and second paths 302, 304, whilein other approaches, the first and second paths 302, 304 may be arrangedprimarily for guiding and separate structures may form the input andoutput coupling structures 310, 314, 318, 322.

FIG. 4 shows a top cross-sectional view of another embodiment includinga first path 302 for guiding energy at a first plasmon frequency, asecond path 304 for guiding energy at a second plasmon frequency, wherethe first path 302 and the second path 304 form an intersection region306 that forms a first portion of the first path 302. In this case,particles 402 having a first size form the first path 302, particles 404having a second size form the second path 304, and an ellipticalparticle 406 forms the intersection region 306. The particle 406 formingthe intersection region 306 is configured to resonate at both the firstplasmon frequency and the second plasmon frequency. In this case theintersection region 306 includes a single elliptical particle 406configured to resonate at two frequencies, however, other assemblies mayresonate at two or more frequencies, including triangular particles,assemblies of two or more particles, or a different configuration.Further, other embodiments allow the first path 302 to guide energy at afirst plasmon frequency and the second path 304 to guide energy at asecond plasmon frequency, for example, by varying the size, shape,material, and/or other parameters of the particles 402, 404.

Incoming electromagnetic energy 412 is converted into a plasmon 102(shown on particles 202 in FIG. 2) that propagates along the first path302. Plasmons 102 that pass through the intersection region 306 are thenconverted into outgoing electromagnetic energy 416. Similarly, incomingelectromagnetic energy 420 is converted into a plasmon 102 thatpropagates along the second path 304. Plasmons 102 that pass through theintersection region 306 are then converted into outgoing electromagneticenergy 424. Electromagnetic energy 420 converted into a plasmon 102propagating along the second path 304 can saturate the ellipticalparticle 406. The saturated elliptical particle 406 does not supportpropagation of plasmon energy, and thus inhibits propagation of theplasmon 102 through the intersection region 306 along the first path302.

The embodiment in FIG. 4 is shown having paths 302, 304 with differentsize particles 402, 404, however in some embodiments the paths 302, 304may have substantially the same size particles 402, 404. Further,although the embodiment is described such that plasmon propagation alongthe second path 304 blocks plasmon propagation along the first path 302,the reverse may be the case, where plasmon propagation along the firstpath 302 blocks plasmon propagation along the second path 304.

The embodiment in FIG. 4 is further described such that plasmonspropagating along one path and saturating the particle 406 forming theintersection region 306 block plasmons from propagating along adifferent path. However, in some embodiments plasmons propagating alongone path may block only a portion of the plasmon energy propagatingalong a different path such that the amount of plasmon energypropagating on one path determines the amount of plasmon energy that maypropagate on the other path. In such an approach, the relationshipbetween the amount of plasmon energy along the second path 304 and theamount of plasmon energy that propagates along the first path 302 is notnecessarily binary. That is, the amount of plasmon energy that passesthe elliptical particle 406 can be an analog function of the amount ofplasmon energy arriving at the elliptical particle 406 along the secondpath 304.

FIG. 5 shows a top cross-sectional view of an embodiment of a plasmonlogic element 500 including a first plasmon guide 502 extending from aninput location 504 to an output location 506 and a firstelectromagnetically nonlinear structure 508 interposed at a firstcentral location 510 (analogous to the intersection region 306 thatforms a first portion of the first path 302) intermediate to the inputlocation 504 and output location 506, where the first nonlinearstructure 508 is responsive to electromagnetic energy 512 to controlplasmon propagation past the first central location 510. An energyguiding structure 514 is configured to guide the electromagnetic energy512 to the first central location 510. An input coupling structure 310is configured to convert incoming electromagnetic energy 312 into aplasmon 102 (shown in FIG. 1) that propagates along the first plasmonguide 502, and an output coupling structure 314 is configured to converta plasmon 102 propagating along the first plasmon guide 502 intooutgoing electromagnetic energy 316.

In the embodiment shown in FIG. 5, the energy guiding structure 514 isan optical fiber configured to direct energy substantially in theoptical frequency range to the first central location 510. In otherembodiments, the type of energy guiding structure 514 may be determinedby the frequency response of the first nonlinear structure 508. Forexample, the energy guiding structure may include an integrated opticalwaveguide, a set of particles, a carbon nanotube structure, adielectric-dielectric interface, or any other appropriate structure thatcan guide the energy. In one embodiment, the energy guiding structure514 may be configured to carry electromagnetic energy in the form of aplasmon 102. In another embodiment, the energy guiding structure 514 canbe removed and electromagnetic energy 512 can be directed toward thefirst nonlinear structure 508 through freespace or another transmissivemedium. Or, electromagnetic energy 512 can emitted substantiallyadjacent to the first nonlinear structure, with a light emissive orplasmon emissive structure, such as a laser or another known form oflocally emitting energy at the appropriate frequency.

FIG. 6 shows a top cross-sectional view of another embodiment of aplasmon logic element 500 including a first plasmon guide 502 extendingfrom an input location 504 to an output location 506 and a firstelectromagnetically nonlinear structure 508 interposed at a firstcentral location 510 intermediate to the input location 504 and outputlocation 506, where the first nonlinear structure 508 is responsive toelectromagnetic energy 512 to control plasmon propagation past the firstcentral location. In the embodiment shown in FIG. 6, the first plasmonguide 502 includes an array of particles 202 and the electromagneticallynonlinear structure 508 is a metallic particle coated with nonlinearmaterial as described with respect to FIG. 2. However, in otherembodiments the electromagnetically nonlinear structure 508 may be adifferent structure configured to support plasmons and to saturate undercertain conditions.

Although the embodiment in FIG. 6 shows only one particle 508 includingnonlinear material, more than one particle in the guide 502 may includea nonlinear material, as described with respect to FIG. 2. Further,other variations may include those described with respect to FIG. 2. Inan embodiment where more than one particle in the guide 502 includes anonlinear material, electromagnetic energy 512 incident on the guide 502can select the first central location 510 on the guide 502 where plasmonpropagation is controlled. Or, a second particle 202 in the guide 502coated with a nonlinear material may function as a secondelectromagnetically nonlinear structure at a second central location(not shown), where plasmon propagation along the guide 502 may becontrolled at both the first central location and the second centrallocation.

FIG. 7 shows a system including an embodiment similar to that in FIG. 3,where the system includes an energy generator 702 configured to produceenergy. The input coupling structure 310 is configured to couple theenergy from the energy generator 702 to a plasmon 102 (shown in FIG. 1).In one embodiment, the energy generator 702 may be a device configuredto produce electromagnetic energy, such as a laser, and the inputcoupling structure 310 may include a converter configured to convertenergy to a plasmon 102. Although the energy generator 702 is shownseparate from the first path 302, in some embodiments the first path 302may include the energy generator 702. Sources of electromagneticradiation that may be included in the first path 302 are known to thoseskilled in the art, and may include a microcavity semiconductor lasersuch as that described in U.S. Pat. No. 5,825,799, entitled MICROCAVITYSEMICONDUCTOR LASER, to Seng-Tiong Ho, Daniel Yen Chu, Jian-Ping Zhang,and Shengli Wu, which is incorporated herein by reference.

FIG. 7 further includes the output coupling structure 314, where theoutput coupling structure 314 may include a converter configured toconvert a plasmon 102 into a different form of energy such aselectromagnetic energy, and/or a region arranged to output the energy.FIG. 7 further includes a detector 704, where the detector 704 mayinclude a device configured to detect electromagnetic energy, such as aphotodetector or other detector, or the detector 704 may be configuredto detect a different kind of energy, depending on the type of energyoutput from the output coupling structure 314. Although FIG. 7 includesan input coupling structure 310 and an output coupling structure 314, insome embodiments these may not be included, for example, where theenergy generator 702 is within the first path 302, the input couplingstructure 310 may not be included.

FIG. 7 further includes a second energy generator 706, a second inputcoupling structure 318, a second output coupling structure 322, and asecond detector 708. The second input coupling structure 318 isconfigured to couple the energy from the second energy generator 706 toa plasmon 102. In one embodiment, the second energy generator 706 may bea device configured to produce electromagnetic energy, such as a laser,and the second input coupling structure 318 may include a converterconfigured to convert energy to a plasmon 102. Although the secondenergy generator 706 is shown separate from the second path 304, in someembodiments the second path 304 may include the energy generator.

The second output coupling structure 322 may include a converterconfigured to convert a plasmon 102 into a different form of energy suchas electromagnetic energy, and/or a region arranged to output theenergy. The second detector 708 is configured to receive energy from thesecond output coupling structure 322 and may include a device configuredto detect electromagnetic energy, such as a photodetector or otherdetector, or the second detector 708 may be configured to detect adifferent kind of energy, depending on the type of energy output fromthe second output coupling structure 322. Although FIG. 7 includes asecond input coupling structure 318 and a second output couplingstructure 322, in some embodiments these may not be included, forexample, where the second energy generator 706 is within the second path304, the second input coupling structure 318 may not be included.

FIG. 7 further includes a processor 710 operably connected to the energygenerator 702, the detector 704, the second energy generator 706, andthe second detector 708. The processor 710 may be connected directly tothe elements 702, 704, 706, 708, and/or there may be intermediatedevices. Further, there may be more than one processor 710. Although theprocessor 710 is shown only in FIG. 7, any of the embodiments mayinclude a processor 710, where the processor 710 may be operably coupledto elements of the system, where the elements are not limited to thosedescribed above.

Although the processor of FIG. 7 is described with reference to FIG. 3,the corresponding structures, methods, systems, and apparatuses can beused in conjunction with any of the embodiments. Moreover, although theembodiment of FIG. 7 illustrates a single processors and a singlegeneration, the structures, methods, systems, and apparatuses herein mayinclude one or more energy generators 702, 706 and/or detectors 704,708, and/or processor(s) 710. A processor may include electricalcircuitry and/or other apparatuses for processing signals.

FIG. 8 shows a top cross-sectional view of an embodiment similar to thatof FIG. 5, further including a second electromagnetically nonlinearstructure 802 interposed at a second central location 804 intermediateto the input location 504 and output location 506. Although theembodiment shown in FIG. 8 does not include the energy guiding structure514, in other embodiments it may include an energy guiding structure 514configured to guide energy to the first central location 510, and/or itmay include a second energy guiding structure (not shown) configured toguide energy to the second central location 804.

As described with respect to FIG. 5, the input coupling structure 310 isconfigured to convert incoming electromagnetic energy 312 into a plasmon102 (shown in FIG. 1), and the output coupling structure 314 isconfigured to convert a plasmon 102 into outgoing electromagnetic energy316. In the embodiment shown in FIG. 8, the first and second centrallocations 510, 804 both include an electromagnetically nonlinearstructure configured to saturate when electromagnetic energy 512 or 806is incident on it. Thus a plasmon 102 may propagate along the firstplasmon guide 502 through the first and second central locations 510,804 when electromagnetic energy 512, 806 is not incident on the firstand second central locations 510, 804, and when electromagnetic energy512 or 806 is incident on one of the first and second central locations510, 804, the plasmon 102 may not propagate through the first and/orsecond central locations 510, 804. Thus electromagnetic energy 512 or806 incident on either the first or second central location 510 or 806can inhibit electromagnetic energy 316 from being detected by thedetector 704. Although the embodiment shown in FIG. 8 includes twoelectromagnetically nonlinear structures 508 and 802, the system may beconfigured with any number of these. Further, although the first andsecond central locations 510, 804 are shown as small, rectilinearportions of the first plasmon guide 502, they may be shaped differentlydepending upon the design considerations.

FIG. 9 shows a top cross-sectional view of another embodiment similar tothat in FIG. 5, further including a second electromagnetically nonlinearstructure 802 and a second output location 902 located on one branch ofa ‘Y’ shaped structure, wherein the second electromagnetically nonlinearstructure 802 is interposed at a second central location 904intermediate to the input location 504 and the second output location902.

The input coupling structure 310 is configured to convert incomingelectromagnetic energy 312 into a plasmon 102 (shown in FIG. 1), and theoutput coupling structures 314, 906 are each configured to convert aplasmon 102 into outgoing electromagnetic energy 316, 908.

In the embodiment shown in FIG. 9, the first and second centrallocations 510, 904 both include an electromagnetically nonlinearstructure 508, 802 configured to saturate when electromagnetic energy512 or 910 is incident on it. Thus a plasmon 102 may propagate along thefirst plasmon guide 502 through the first and second central locations510, 904 when electromagnetic energy 512, 910 is not incident on thefirst and second central locations 510, 904. When electromagnetic energy512 is incident on the first central location 510 the plasmon 102 maynot propagate through the first central location 510, and thuselectromagnetic energy 512 incident on the first central location 510can inhibit electromagnetic energy 316 from being detected by thedetector 704. Similarly, when electromagnetic energy 910 is incident onthe second central location 904 the plasmon 102 may not propagatethrough the second central location 904, and thus electromagnetic energy910 incident on the second central location 904 can inhibitelectromagnetic energy 908 from being detected by the detector 912. Or,when electromagnetic energy 512, 910 is incident on both the firstcentral location and the second central location 510 and 904 the plasmon102 may not propagate through either the first or second centrallocations 510 or 904, and thus electromagnetic energy 512, 910 incidenton the first and second central locations 510 and 904 can inhibitelectromagnetic energy 316 and 908 from being detected by the detectors704 and 912.

Although the embodiment shown in FIG. 9 includes two electromagneticallynonlinear structures 508 and 802, the system may be configured with anynumber of these. Further, although the first and second centrallocations 510, 904 are shown as small, rectilinear portions of the firstplasmon guide 502, they may be configured in a different shape.

In the embodiment shown in FIG. 10, an electromagnetically nonlinearstructure 508 is configured on a fiber 1002 having an outer conductivelayer 1004, where the fiber 1002 forms a first plasmon guide 502extending from an input location 504 to an output location 506, andwhere the first electromagnetically nonlinear structure 508 isinterposed at a first central location 510 intermediate to the inputlocation 504 and output location 506. The first electromagneticallynonlinear structure 508 is fabricated on the conductive layer 1004,where the first nonlinear structure 508 is responsive to electromagneticenergy 512 to control plasmon propagation past the first centrallocation 510.

Electromagnetic energy 312 is coupled into and propagates in the fiber1002 and couples to an evanescent wave in the conductive layer 1004,which couples to a plasmon 102 (shown in FIG. 1) on an outer surface1006 of the conductive layer 1004. The conductive layer 1004 may includea high conductivity metal such as silver, gold, or copper, or it may beanother type of metal or conductive material. Metal-coated fibers areknown to those skilled in the art and various methods exist for coatinga fiber with metal, including vacuum evaporation and sputtering.

Although the fiber 1002 in FIG. 10 has a substantially circularcross-section 1008 that remains substantially constant along the length1010 of the fiber 1002, the fiber 1002 may have any shape, including butnot limited to irregular cross-sections 1008 and/or cross-sections 1008that vary along the length 1010.

A first embodiment of a plasmon gate 1100, shown in FIG. 11 (and similarto the embodiment shown in FIG. 8), comprises a first plasmon guide 502extending from an input location 504 to an output location 506, a firstplasmon switch 1102 interposed at a first central location 510intermediate the input location 504 and output location 506 andresponsive to a first signal 1106, and a second plasmon switch 1104interposed at a second central location 804 intermediate the inputlocation 504 and output location 506 and responsive to a second signal1108, wherein the first switch 1102 and the second switch 1104 arearranged to control plasmon propagation to the output location 506. Theinput coupling structure 310 is configured to convert incomingelectromagnetic energy 312 into a plasmon 102 (shown in FIG. 1), and theoutput coupling structure 314 is configured to convert a plasmon 102into outgoing electromagnetic energy 316.

A table 1200 (truth table) shown in FIG. 12 further illustrates theoperation of the plasmon gate 1100. In the example shown in FIG. 11,when the first signal 1106 is incident on the first plasmon switch 1102,a plasmon 102 is inhibited from passing through the switch 1102,representing a ‘0’ in the table 1200. When the first signal 1106 is notincident on the first plasmon switch 1102, a plasmon 102 may propagatethrough the switch 1102, representing a ‘1’ in the table 1200.

Similarly, when the second signal 1108 is incident on the second plasmonswitch 1104, a plasmon 102 is inhibited from passing through the switch1104, representing a ‘0’ in the table 1200, and when the second signal1108 is not incident on the second plasmon switch 1104, a plasmon 102may propagate through the switch 1104, representing a ‘1’ in the table1200.

Thus a plasmon 102 may propagate along the first plasmon guide 502through the first and second plasmon switches 1102, 1104 when a signal1106, 1108 is not incident on the switches 1102, 1104, allowingelectromagnetic energy 316 to be detected by the detector 704,represented by a ‘1’ in the ‘OUT’ column of the table 1200. When asignal 1106 or 1108 is incident on one of the first and second plasmonswitches 1102, 1104, the plasmon 102 may not propagate through the firstand/or second plasmon switch 1102, 1104. Thus a signal 1106 or 1108incident on either the first or second plasmon switch can inhibitelectromagnetic energy 316 from being detected by the detector 704,represented by a ‘0’ in the ‘OUT’ column of the table 1200.

In a second embodiment of a plasmon gate 1300, shown in FIG. 13, thefirst plasmon guide 502 extends from an input location 504 to an outputlocation 506 and is arranged to route plasmon energy into a first branch1302 and a second branch 1304 at a first intersection location 1306. Thefirst branch 1302 includes the first plasmon switch 1102 responsive to afirst signal 1106 at a first central location 510 and the second branch1304 includes the second plasmon switch 1104 responsive to a secondsignal 1108 at a second central location 804, wherein the first switch1102 and the second switch 1104 are arranged to control plasmonpropagation to the output location 506. The first plasmon guide 502 isarranged to join plasmon energy from the first branch 1302 and thesecond branch 1304 at a second intersection location 1308. The inputcoupling structure 310 is configured to convert incoming electromagneticenergy 312 into a plasmon 102 (shown in FIG. 1), and the output couplingstructure 314 is configured to convert a plasmon 102 into outgoingelectromagnetic energy 316. Although FIG. 13 is shown having twobranches 1302, 1304 and two plasmon switches 1102, 1104, otherembodiments may include three or more branches and/or three or moreswitches, where each switch may be on a different branch or two or moreswitches may be on a single branch.

A table 1400 (truth table) shown in FIG. 14 further illustrates theoperation of the plasmon gate 1300. When the first signal 1106 isincident on the first plasmon switch 1102, a plasmon 102 is inhibitedfrom passing through the switch 1102, representing a ‘0’ in the table1400. When the first signal 1106 is not incident on the first plasmonswitch 1102, a plasmon 102 may propagate through the switch 1102,representing a ‘1’ in the table 1200.

Similarly, when the second signal 1108 is incident on the second plasmonswitch 1104, a plasmon 102 is inhibited from passing through the switch1104, representing a ‘0’ in the table 1200, and when the second signal1108 is not incident on the second plasmon switch 1104, a plasmon 102may propagate through the switch 1104, representing a ‘1’ in the table1400.

Thus, a plasmon 102 may propagate along the first plasmon guide 502through the first and second plasmon switches 1102, 1104 when a signal1106, 1108 is not incident on the switches 1102, 1104, allowingelectromagnetic energy 316 to be detected by the detector 704,represented by a ‘1’ in the ‘OUT’ column of the table 1400. When asignal 1106 or 1108 is incident on one of the first and second plasmonswitches 1102, 1104, the plasmon 102 may propagate through the otherplasmon switch 1102, 1104. For example, when a signal 1106 is incidenton the first plasmon switch 1102, a plasmon 102 may not propagatethrough the first plasmon switch 1102, but it may propagate through thesecond plasmon switch 1104, allowing electromagnetic energy 316 to bedetected by the detector 704, represented by a ‘1’ in the ‘OUT’ columnof the table 1400. A signal 1106 or 1108 incident on both the first orsecond plasmon switch can inhibit electromagnetic energy 316 from beingdetected by the detector 704, represented by a ‘0’ in the ‘OUT’ columnof the table 1400.

With regard to the embodiments shown in FIGS. 11 and 13, the inputcoupling structure 310 is shown as being receptive to electromagneticenergy 312, however in other embodiments the input coupling structure310 may be receptive to a different kind of energy, for example, plasmonenergy. Similarly, the output coupling structure 314 is shown as beingconfigured to output electromagnetic energy 316, but in otherembodiments the output coupling structure 314 may be configured tooutput a different kind of energy, for example, plasmon energy and/orelectromagnetic energy.

The first signal 1106 and/or the second signal 1108 in FIGS. 11 and 13may include electromagnetic energy, plasmon energy, and/or a differentform of energy, depending on the switches 1102, 1104. The first and/orsecond plasmon switch 1102, 1104 may include an electromagneticallynonlinear structure, as described, for example, with respect to FIG. 3.The first plasmon guide 502 may be arranged substantially in a singleplane or it may be configured in a non-planar arrangement.

Although the embodiments shown in FIGS. 11 and 13 do not include anenergy guiding structure 514, other embodiments may include one or moreenergy guiding structures 514 configured to guide energy including thefirst and/or second signal 1106, 1108 to the first and/or second plasmonswitch 1102, 1104.

Although FIGS. 11 and 13 show substantially linear guides, in otherembodiments the first plasmon guide 502 may include at least oneparticle supportive of plasmon energy, as shown in FIGS. 2, 4 and 6.

Although the configuration of the gates 1100 and 1300 represented bytables 1200 and 1400 include switches 1102, 1104 that are represented bya ‘0’ when a signal 1106 or 1108 is incident on them and by a ‘1’ when asignal 1106 or 1108 is not incident on them, the switches may beconfigured such that a signal 1106 or 1108 incident on them isrepresented by a ‘1’ and a signal 1106 or 1108 not incident on them isrepresented by a ‘0’, and one skilled in the art may select andconfigure switches to produce a gate having a desired functionaldependence. Further, although the tables 1200 and 1400 representfunctions that are substantially constant in time, in other embodimentsgates 1100, 1300 may be configured such that they are represented byfunctions that vary as a function of time. For example, in oneembodiment, the switches 1102, 1104 may be configured to be responsiveto a time-varying signal (not shown) such as a time-varyingelectromagnetic signal, electric or magnetic field, mechanical stress orstrain, or a different time-varying stimulus, where the time-varyingsignal changes the properties of the switch as a function of time.

Although the embodiments shown in FIGS. 11 and 13 each include twoplasmon switches 1102, 1104, other embodiments may have differentnumbers of switches. Further, although the first and second centrallocations 510, 804 are shown as small, rectilinear portions of the firstplasmon guide 502, they may be shaped differently depending upon thedesign considerations.

In one embodiment a method of controlling energy propagation comprisesguiding energy at a first plasmon frequency along a first path (or firstplasmon guide 502), blocking the guided energy at the first plasmonfrequency from propagating along the first path 502 responsive to afirst signal 1106 at a first time, blocking the guided energy at thefirst plasmon frequency from propagating along the first path 502responsive to a second signal 1108, different from the first signal1106, at a second time, and receiving an output (for example, theoutgoing electromagnetic energy 316) that is a function of the firstsignal 1106 and the second signal 1108. The second time may follow thefirst time, may be substantially the same as the first time, or mayprecede the first time. The embodiment may further comprise guidingenergy at a second plasmon frequency along the first path 502.

The method may further comprise, at a first location (or firstintersection location 1306) on the first path 502, directing a firstportion of the energy at the first plasmon frequency into a first branch1302, directing a second portion of the energy at the first plasmonfrequency into a second branch 1304, and/or combining the first portionof the energy at the first plasmon frequency from the first branch 1302and the second portion of the energy at the first plasmon frequency fromthe second branch 1304 at a second location (or second intersectionlocation 1308) on the first path. The method may further compriseapplying the first signal 1106 to the first branch 1302 and/or applyingthe second signal 1108 to the second branch 1304.

The method may further comprise coupling electromagnetic energy to thefirst path 502, generating the electromagnetic energy, coupling plasmonenergy to the first path 502, generating the plasmon, and/or generatinga plasmon along the first path. The method may further comprisegenerating the first and/or second signal 1106, 1108, and/or guiding thefirst and/or second signal 1106, 1108. The method may further comprisedetecting, storing, and/or sending the output 316.

Blocking the guided energy at the first plasmon frequency frompropagating along the first path 502 responsive to a first signal 1106may include saturating a first portion of the first path (or firstcentral location 510) with the first signal 1106 and, similarly,blocking the guided energy at the first plasmon frequency frompropagating along the first path 502 responsive to a second signal 1108may include saturating a second portion of the first path (or secondcentral location 804) with the second signal 1108.

In one embodiment, a method comprises inputting a plasmon signal,selectively controlling the plasmon signal with a plurality of controlsignals (a first signal 1106 and a second signal 1108), and outputting aplasmon signal having a distribution that is a function of the pluralityof control signals. The distribution may be a spatial distribution, atemporal distribution, or a different kind of distribution. It may be afunction of the input plasmon signal, where the function may besubstantially described by a table such as those in FIGS. 12 and 14and/or may vary in time. The method may comprise generating at least oneof the plurality of control signals 1106, 1108, where at least one ofthe plurality of control signals 1106, 1108 may include plasmon energyand/or at least one of the plurality of control signals may includeelectromagnetic energy.

In one embodiment, an apparatus such as the plasmon gate 1100 comprisesa plasmon input (or input location 504) receptive to a first plasmonsignal, a first control input (or first plasmon switch 1102) receptiveto a first control signal (the first signal 1106), a second controlinput (or second plasmon switch 1104) receptive to a second controlsignal (the second signal 1108), and a plasmon output (or outputlocation 506) configured to output a second plasmon signal as a functionof the first plasmon signal, the first control signal 1106 and thesecond control signal 1108. The embodiment may further comprise a thirdcontrol input receptive to a third control signal, not shown. The firstcontrol input 1102 may be further receptive to a third control signal,also not shown. The function of the first plasmon signal, the firstcontrol signal 1106 and the second control signal 1108 is substantiallydescribed by a table such as the tables 1200 and 1400 in FIGS. 12 and14, where the table may describe an OR gate, an AND gate, or a differentkind of gate.

Although the embodiments described in FIGS. 1-14 are generally describedsuch that saturation of a region and/or energy incident on a nonlinearmaterial inhibits propagation of a plasmon 102 through the region and/ormaterial, in other embodiments saturation of a region and/or energyincident on a nonlinear material may be configured to allow propagationof a plasmon 102, and no saturation of a region and/or energy notincident on a nonlinear material may be configured to inhibit and/orrestrict propagation of a plasmon 102.

In this disclosure, references to “optical” elements, components,processes or other aspects, as well as references to “light” may alsorelate in this disclosure to so-called “near-visible” light such as thatin the near infrared, infra-red, far infrared and the near and farultra-violet spectrums. Moreover, many principles herein may be extendedto many spectra of electromagnetic radiation where the processing,components, or other factors do not preclude operation at suchfrequencies, including frequencies that may be outside ranges typicallyconsidered to be optical frequencies.

Although FIGS. 1-14 show structures configured to transport energy overrelatively short distances, in some embodiments structures may beconfigured to transport energy over very long distances of eventhousands of kilometers or more. For example, referring to FIG. 10, anoptical fiber may be configured to carry electromagnetic energy over asubstantially large distance, and metal deposited on the fiber mayconvert energy from electromagnetic energy propagating in the fiber toplasmon energy propagating on the metal.

Applications of plasmons and logic systems including plasmons are wideranging. For example, there may be situations, such as in optical fibersystems where all-optical switching is desired, where electromagneticenergy is converted to plasmons to do the switching and then convertedback to electromagnetic energy.

Although the term “plasmon” is used to describe a state propagating atthe boundary between two materials whose real parts of their dielectricconstant ∈ and ∈′ have different signs, one skilled in the art mayrecognize that other terms may exist for this state, including, but notlimited to, “surface plasmon” and/or “surface plasmon polariton”.

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, or examples can be implemented,individually and/or collectively, by a wide range of hardware, software,firmware, or virtually any combination thereof. In one embodiment,several portions of the subject matter described herein may beimplemented via Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs), digital signal processors (DSPs), orother integrated formats. However, those skilled in the art willrecognize that some aspects of the embodiments disclosed herein, inwhole or in part, can be equivalently implemented in integratedcircuits, as one or more computer programs running on one or morecomputers (e.g., as one or more programs running on one or more computersystems), as one or more programs running on one or more processors(e.g., as one or more programs running on one or more microprocessors),as firmware, or as virtually any combination thereof, and that designingthe circuitry and/or writing the code for the software and or firmwarewould be well within the skill of one of skill in the art in light ofthis disclosure. In addition, those skilled in the art will appreciatethat the mechanisms of the subject matter described herein are capableof being distributed as a program product in a variety of forms, andthat an illustrative embodiment of the subject matter described hereinapplies regardless of the particular type of signal bearing medium usedto actually carry out the distribution. Examples of a signal bearingmedium include, but are not limited to, the following: a recordable typemedium such as a floppy disk, a hard disk drive, a Compact Disc (CD), aDigital Video Disk (DVD), a digital tape, a computer memory, etc.; and atransmission type medium such as a digital and/or an analogcommunication medium (e.g., a fiber optic cable, a waveguide, a wiredcommunications link, a wireless communication link, etc.).

In a general sense, those skilled in the art will recognize that thevarious embodiments described herein can be implemented, individuallyand/or collectively, by various types of electro-mechanical systemshaving a wide range of electrical components such as hardware, software,firmware, or virtually any combination thereof, and a wide range ofcomponents that may impart mechanical force or motion such as rigidbodies, spring or torsional bodies, hydraulics, and electro-magneticallyactuated devices, or virtually any combination thereof. Consequently, asused herein “electro-mechanical system” includes, but is not limited to,electrical circuitry operably coupled with a transducer (e.g., anactuator, a motor, a piezoelectric crystal, etc.), electrical circuitryhaving at least one discrete electrical circuit, electrical circuitryhaving at least one integrated circuit, electrical circuitry having atleast one application specific integrated circuit, electrical circuitryforming a general purpose computing device configured by a computerprogram (e.g., a general purpose computer configured by a computerprogram which at least partially carries out processes and/or devicesdescribed herein, or a microprocessor configured by a computer programwhich at least partially carries out processes and/or devices describedherein), electrical circuitry forming a memory device (e.g., forms ofrandom access memory), electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment), and any non-electrical analog thereto, such as optical orother analogs. Those skilled in the art will also appreciate thatexamples of electro-mechanical systems include but are not limited to avariety of consumer electronics systems, as well as other systems suchas motorized transport systems, factory automation systems, securitysystems, and communication/computing systems. Those skilled in the artwill recognize that electro-mechanical as used herein is not necessarilylimited to a system that has both electrical and mechanical actuationexcept as context may dictate otherwise.

In a general sense, those skilled in the art will recognize that thevarious aspects described herein which can be implemented, individuallyand/or collectively, by a wide range of hardware, software, firmware, orany combination thereof can be viewed as being composed of various typesof “electrical circuitry.” Consequently, as used herein “electricalcircuitry” includes, but is not limited to, electrical circuitry havingat least one discrete electrical circuit, electrical circuitry having atleast one integrated circuit, electrical circuitry having at least oneapplication specific integrated circuit, electrical circuitry forming ageneral purpose computing device configured by a computer program (e.g.,a general purpose computer configured by a computer program which atleast partially carries out processes and/or devices described herein,or a microprocessor configured by a computer program which at leastpartially carries out processes and/or devices described herein),electrical circuitry forming a memory device (e.g., forms of randomaccess memory), and/or electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment). Those having skill in the art will recognize that thesubject matter described herein may be implemented in an analog ordigital fashion or some combination thereof.

All of the above U.S. patents, U.S. patent application publications,U.S. patent applications, foreign patents, foreign patent applicationsand non-patent publications referred to in this specification and/orlisted in any Application Data Sheet, are incorporated herein byreference, in their entireties.

One skilled in the art will recognize that the herein describedcomponents (e.g., steps), devices, and objects and the discussionaccompanying them are used as examples for the sake of conceptualclarity and that various configuration modifications are within theskill of those in the art. Consequently, as used herein, the specificexemplars set forth and the accompanying discussion are intended to berepresentative of their more general classes. In general, use of anyspecific exemplar herein is also intended to be representative of itsclass, and the non-inclusion of such specific components (e.g., steps),devices, and objects herein should not be taken as indicating thatlimitation is desired.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations are not expressly set forth herein for sakeof clarity.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely exemplary, and that in fact many other architectures can beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable”, to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

While particular aspects of the present subject matter described hereinhave been shown and described, it will be apparent to those skilled inthe art that, based upon the teachings herein, changes and modificationsmay be made without departing from the subject matter described hereinand its broader aspects and, therefore, the appended claims are toencompass within their scope all such changes and modifications as arewithin the true spirit and scope of the subject matter described herein.Furthermore, it is to be understood that the invention is defined by theappended claims. It will be understood by those within the art that, ingeneral, terms used herein, and especially in the appended claims (e.g.,bodies of the appended claims) are generally intended as “open” terms(e.g., the term “including” should be interpreted as “including but notlimited to,” the term “having” should be interpreted as “having atleast,” the term “includes” should be interpreted as “includes but isnot limited to,” etc.). It will be further understood by those withinthe art that if a specific number of an introduced claim recitation isintended, such an intent will be explicitly recited in the claim, and inthe absence of such recitation no such intent is present. For example,as an aid to understanding, the following appended claims may containusage of the introductory phrases “at least one” and “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

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 27. A plasmon gate, comprising: a firstplasmon guide extending from an input location to an output location; afirst optical control guide electromagnetically proximate a firstcentral location intermediate the input location and output location,and configured to direct a first optical control signal to the firstcentral location; a first plasmon switch interposed at the first centrallocation and responsive to a the first optical control signal toselectively control plasmon propagation past the first central location;a second optical control guide electromagnetically proximate a secondcentral location intermediate the input location and output location,and configured to direct a second optical control signal to the secondcentral location; and a second plasmon switch interposed at the secondcentral location and responsive to the second optical signal, whereinthe first switch and the second switch are arranged to cooperativelycontrol plasmon propagation to the output location.
 28. The plasmon gateof claim 27 wherein the first plasmon switch includes anelectromagnetically nonlinear structure that is nonlinearly responsiveto the first optical control signal.
 29. The plasmon gate of claim 27wherein the second plasmon switch includes an electromagneticallynonlinear structure that is nonlinearly responsive to the second opticalcontrol signal.
 30. The plasmon gate of claim 27 wherein the firstplasmon guide is arranged substantially in a single plane.
 31. Theplasmon gate of claim 27 further comprising an input coupling structureat the input location.
 32. The plasmon gate of claim 31 wherein theinput coupling structure is receptive to plasmon energy.
 33. The plasmongate of claim 31 wherein the input coupling structure is receptive toelectromagnetic energy.
 34. The plasmon gate of claim 33 furthercomprising a converter arranged to convert electromagnetic energy toplasmon energy.
 35. The plasmon gate of claim 27 further comprising anoutput coupling structure at the output location.
 36. The plasmon gateof claim 35 wherein the output coupling structure is configured tooutput plasmon energy.
 37. The plasmon gate of claim 35 wherein theoutput coupling structure is configured to output electromagneticenergy.
 38. The plasmon gate of claim 37 further comprising a converterarranged to convert plasmon energy to electromagnetic energy.
 39. Theplasmon gate of claim 27 wherein the first plasmon guide includes atleast one particle supportive of plasmon energy.
 40. The plasmon gate ofclaim 27 wherein the first plasmon guide is arranged to route plasmonenergy into a first branch and a second branch at a first intersectionlocation.
 41. The plasmon gate of claim 40 wherein the first centrallocation includes the first intersection location.
 42. The plasmon gateof claim 40 wherein the first branch includes the first central locationand the second branch includes the second central location.
 43. Theplasmon gate of claim 42 wherein the first plasmon guide is arranged tojoin plasmon energy from the first branch and the second branch at asecond intersection location.
 44. The plasmon gate of claim 27 furthercomprising a third plasmon switch interposed at a third central locationintermediate the input location and output location and responsive to athird signal, wherein the third plasmon switch is configured to controlplasmon propagation to the output location with the first and secondplasmon switches.
 45. The plasmon gate of claim 27 further comprising afirst energy guide arranged to guide energy to the first centrallocation.
 46. The plasmon gate of claim 27 further comprising a secondenergy guide arranged to guide energy to the second central location.47. (canceled)
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 62. A plasmon gate, comprising: a firstplasmon guide extending from an input location to an output location; afirst optical control guide electromagnetically proximate a firstcentral location intermediate the input location and output location,and configured to direct a first optical control signal to the firstcentral location; a first plasmon switch interposed at the first centrallocation and responsive to the first optical control signal toselectively control plasmon propagation past the first central location,wherein the first plasmon switch includes an electromagneticallynonlinear structure that is nonlinearly responsive to the first opticalcontrol signal; and a second plasmon switch interposed at a secondcentral location intermediate the input location and output location andresponsive to a second optical signal, wherein the first switch and thesecond switch are arranged to cooperatively control plasmon propagationto the output location.
 63. The plasmon gate of claim 62 furthercomprising a second optical control guide electromagnetically proximatethe second central location and configured to direct the second opticalcontrol signal to the second central location.
 64. The plasmon gate ofclaim 62 wherein the second plasmon switch includes anelectromagnetically nonlinear structure that is nonlinearly responsiveto the second optical control signal.
 65. The plasmon gate of claim 62wherein the first optical control guide includes an optical fiber.
 66. Aplasmon gate, comprising: a first plasmon guide extending from an inputlocation to an output location; a first optical control guideelectromagnetically proximate a first central location intermediate theinput location and output location, and configured to direct a firstoptical control signal to the first central location; a first plasmonswitch including an electromagnetically nonlinear structure andinterposed at the first central location and nonlinearly responsive tothe first optical control signal to selectively control plasmonpropagation past the first central location; a second optical controlguide electromagnetically proximate a second central locationintermediate the input location and output location, and configured todirect a second optical control signal to the second central location;and a second plasmon switch including an electromagnetically nonlinearstructure and interposed at the second central location and nonlinearlyresponsive to the second optical signal, wherein the first switch andthe second switch are arranged to cooperatively control plasmonpropagation to the output location.